/Engine/Source/Runtime/MeshDescription/Public/MeshDescription.h
Set the vertex instance at the given index around the polygon to the new value
void SetPolygonVertexInstances ( const [FPolygonID](API\Runtime\MeshDescription\FPolygonID) PolygonID, [TArrayView](API\Runtime\Core\Containers\TArrayView)< const [FVertexInstanceID](API\Runtime\MeshDescription\FVertexInstanceID) > VertexInstanceIDs )